What's the difference between incubus and succubus?

Incubus

Definition:

(n.) A demon; a fiend; a lascivious spirit, supposed to have sexual intercourse with women by night.
(n.) The nightmare. See Nightmare.
(n.) Any oppressive encumbrance or burden; anything that prevents the free use of the faculties.

Example Sentences:

(1) It contains chapters on modern syndromes, eg, headache, paralysis, epilepsy, and vertigo, as well as disorders of the time, eg, incubus and phrenitide.
(2) A private incubus squatting on an anaesthetised public space.
(3) Aside from the punk icon, the cast also includes *NSYNC's JC Chasez as Pontius Pilate, Destiny Child 's Michelle Williams as Mary Magdalene and Incubus frontman and long time fan, Brandon Boyd, who has been cast as Judas Iscariot.
(4) It was to star Lydon as King Herod, Williams as Mary Magdalene, Brandon Boyd of Incubus as Judas and JC Chasez of 'N Sync as Pontius Pilate.
(5) Santa, hard at work in his orbiting space castle (don't ask) is powerless to help as the campy incubus schemes to corrupt virtuous little boys and girls.
(6) The term "incubus syndrome" is proposed to describe patients suffering from the delusion that they have been sexually approached at night by an unseen lover.

Definition:

(n.) A demon or fiend; especially, a lascivious spirit supposed to have sexual intercourse with the men by night; a succuba. Cf. Incubus.
(n.) The nightmare. See Nightmare, 2.

Example Sentences:

(1) Gaskell took Charlotte Brontë, the author of Jane Eyre, the dirtiest, darkest, most depraved fantasy of all time, and, like an angel murdering a succubus, trod on her.
(2) Scarlett Johansson plays the succubus who comes to question the need for all this man-eating.
(3) Yet despite being a malevolent ink-and-paper succubus that will devour your firstborn – seriously, chuck a baby at a copy of the Mail, and watch as the paper roll its eyes back and swallows it whole – the Mail deserves its voice.
(4) Mrs Robinson would be happy to destroy Benjamin, and soon becomes a vengeful maternal succubus, the cold, strict prohibitive mother who punishes for no reason apart from her own pleasure.